Assessing the Nation's Drug Abuse Problems

Annual student surveys track use of drugs like ecstasy, a popular dance party drug.

Discovering and disseminating useful information on the nature and extent of drug abuse has always been a major focus of NIDA's epidemiological research program. Soon after its inception, the Institute launched the Community Epidemiology Work Group (CEWG) and the Monitoring the Future (MTF) surveys to track nationwide trends and patterns in drug use.

Keeping a pulse on the Nation's drug use has yielded critical information. For instance, CEWG, a nationwide epidemiological network that monitors trends in drug abuse in 21 U.S. cities, sounded an early alarm in the 1990s: MDMA, a dangerous drug also known as ecstasy, was becoming the drug of choice for many young patrons of nightclubs and large parties called raves. MTF, an annual survey of drug abuse among America's students, confirmed the threat, noting that while abuse of most illicit drugs was leveling off or declining slightly among youth, ecstasy use was rising among 10th- and 12-graders. In response, NIDA launched the Club Drug Initiative to boost MDMA research and broadcast the dangers of this drug. The effort culminated in 2001 with a NIDA-sponsored conference that focused international research attention on worldwide increases in young people's use of ecstasy.

Since its founding, CEWG has helped establish State and international work groups to extend its critical early drug-warning systems to individual States and most regions of the world. Meanwhile, MTF, which began collecting data on drug use among high school seniors in 1975, broadened its scope in 1991 to include data on 8th- and 10th-graders. Augmenting these data are biennial followup surveys of selected samples of college students and young adults from each senior class.

Policymakers and researchers rely on this information to assess the need for and effectiveness of community- and school-based drug prevention programs. To supplement CEWG and MTF data, NIDA has built a program of ethnographic, cross-sectional, and long-term studies that provides continuous detailed information on patterns of drug use by gender, sexual orientation, race and ethnicity, age, and region.

Addressing the Health Impacts of Drug Abuse

HIV/AIDS and other infectious diseases--such as hepatitis B and C, tuberculosis, and sexually transmitted diseases--multiply the devastation drug abuse and addiction wreak on individuals, their families, and communities. In the past decade, NIDA has provided worldwide leadership in demonstrating how drug abuse spreads these diseases and in developing effective approaches to reducing behaviors that feed transmission.

Along with drug treatment, two national NIDA-developed community outreach programs have demonstrated they can reduce disease-transmitting drug-use practices and sexual behaviors among the 7 of 10 injection drug users not in treatment for their addiction. This research has helped NIDA develop a model community-based AIDS prevention program, whereby street-based outreach workers encourage abusers to enter treatment, offer them HIV testing and counseling, and inform them about ways to reduce sharing drug-injection equipment and engaging in high-risk sexual practices, such as unprotected sex.

Current studies on social interactions among drug abusers and their impact on initiation into injection drug use and other high-risk drug use and sexual behaviors hold great promise for further reducing transmission of infectious diseases. This research points to more effective interventions linked to gender, race, and ethnicity factors to help reduce the risk of disease transmission among specific abuser groups and those they know. For example, recent research suggests that counseling African-American women who inject drugs or smoke crack cocaine on strategies to negotiate less risky sexual behaviors with their partners can increase the effectiveness of NIDA's standard AIDS risk-reduction program.

Tracing the Effects of Prenatal Exposure to Drugs

Addressing maternal drug abuse and its effects on infants and children has always been a key NIDA concern. Basic research begun in the 1970s demonstrated that prenatal exposure to heroin, cocaine, and marijuana can impair the physiological and behavioral development of animals. New animal studies are assessing the effects of prenatal exposure to methamphetamine and MDMA (ecstasy)--drugs increasingly used by women of childbearing age. Several of these studies suggest that prenatal exposure to MDMA can lead to cognitive and behavioral impairments among juvenile offspring, particularly males.

The last decade has found NIDA funding long-term clinical studies to determine how prenatal exposure to illicit drugs interacts with environmental factors to affect the development of infants and children. More than 20 studies have been tracking urban, rural, and suburban infants and children prenatally exposed to narcotics, cocaine, or marijuana. Employing sensitive new assessment tools developed to measure neurobiological and behavioral development, these studies are yielding critical data on how drug-exposed and unexposed children develop, respond to stimuli, play, behave, and learn.

Evidence suggests that prenatal cocaine exposure may produce subtle neurobiological, behavioral, and cognitive impairments in early childhood that may affect later intellectual development. Adequate pre- and postnatal care, a nurturing home environment, and supportive parenting appear to help reduce or compensate for drug-induced damage. More seriously impaired children may require educational intervention when they enter school.

Many questions remain about the future of children prenatally exposed to cocaine, marijuana, and opiates. Thus, NIDA's long-running clinical studies will track these children into adolescence, enabling researchers to identify how biological, behavioral, and environmental factors interact to increase or reduce vulnerability to drug abuse in adolescence. This knowledge will contribute to the development of more advanced prevention strategies.

Understanding the Addicted Brain and Behavior

People with drug addiction compulsively seek and use drugs, despite harmful personal, medical, family, and legal consequences. Three decades of NIDA-supported research has shown that repeated drug abuse causes structural and functional brain changes that drive these destructive choices and behaviors. Rewarding feelings occur the first time a person uses drugs, promoting continued use. In time, more extensive brain changes occur as chronic drug abuse damages nerve cells and alters biochemical signaling mechanisms and communications pathways between networks of these cells. These changes allow abused drugs to hijack basic cognitive and emotional functions that motivate people to pursue normally rewarding activities and redirect them toward one overwhelming goal--experiencing the pleasurable effects of abused drugs.

Dr. Christopher Evans, Duane Keith, and Dr. Robert H. Edwards were part of the UCLA team that cloned the delta opioid receptor, one brain site where morphine binds.

NIDA's molecular, neuroscience, and behavioral research in animals and humans first revealed in the 1970s the primary role the brain plays in drug abuse and addiction. The discovery that both naturally occurring brain chemicals and opiates, such as heroin, act at the same sites in the brain, called receptors, to modulate mood and pain revolutionized thinking about drug addiction and brain function. Building on this insight, NIDA-supported researchers established that drug addiction is a chronic brain disease marked by compulsive drug-seeking, craving during abstinence, and--for many--recurring relapse to drug use during recovery. Discoveries of how abused drugs work in the brain to influence mood, thought, and compulsive drug abuse provide a scientific basis for medications and cognitive-behavioral approaches proven to reduce drug-induced biological and behavioral disruptions, addiction, and its consequences.

In the last decade, NIDA research produced important discoveries about the brain, drug abuse, and other compulsive behaviors at an unprecedented and accelerating pace. Seizing opportunities presented by rapidly advancing research technologies and methodologies in molecular biology and neuroscience, NIDA-supported researchers cloned the genes for the brain receptors through which all major drugs of abuse initiate the complex chain of neurochemical events that produce their addictive effects.

Applying new genetic techniques, researchers reproduced these receptors and used them to develop and test experimental treatment compounds and existing medications for their ability to block or modify the biochemical effects of abused drugs. Scientists also genetically engineered animals that lacked or overproduced these receptors to clarify their role in controlling addictive behaviors, examine how different drugs and compounds affect these behaviors, and mark for possible development as addiction treatment medications those that stop animals from self-administering abused drugs.

The last decade also saw NIDA develop major intramural and extramural programs to apply rapid advances in brain imaging technologies to increase understanding of drug abuse and addiction. Using new positron emission tomography (PET), magnetic resonance imaging (MRI), and electroencephalogram (EEG) techniques, NIDA scientists can view the human brain in action, assess its moment-to-moment responses to drugs, and show the brain damage chronic drug abuse causes. Imaging studies have located large concentrations of receptors linked to drug abuse in specific areas of the brain and detailed how drug addiction changes the structure of these cells and how they function. By linking acute and long-term, drug-induced changes in brain activity to patients' descriptions of their feelings, choices, and behavior, scientists have made large strides in tracing the brain circuitry, structures, and mechanisms by which abused drugs evoke initial reward, compulsive drug abuse, and craving for drugs when use stops.

PET Scans and other imaging techniques show how drugs affect brain activity.

NIDA is now opening new vistas in brain imaging drug abuse research. Studies assessing the ability of potential treatment medications and behavioral treatments to moderate the effects of abused drugs on the brain early in treatment and over the long term will accelerate development of new therapies. Other research examining how genetic variations affect responses to abused drugs will increase knowledge about vulnerability to addiction. Pediatric studies will increase understanding of how prenatal drug exposure, abuse, and addiction affect the developing brain from early childhood through adulthood.

Moving Treatment for Opiate Addiction into Mainstream Medicine

In 2002, the Food and Drug Administration approved buprenorphine, a new medication that is revolutionizing treatment for opiate addiction. Previous opiate treatment medications, such as methadone, can be dispensed only in federally licensed addiction treatment clinics. Buprenorphine is safer than methadone in case of an overdose, can be discontinued more easily, and is less likely to be abused or diverted to illicit use. As a result, patients addicted to heroin and other opiates can be treated by private physicians in their offices--a first in drug abuse treatment.

NIDA-supported basic and clinical studies dating from the early 1970s made possible buprenorphine's development as a medication. Early findings established that heroin and other opiates achieve their euphoric effects by stimulating brain receptors where neurochemicals act to alleviate pain and modulate mood. The concept of drug-receptor interactions provided the basis for a neurobiological understanding of drug addiction and identified molecular targets for medications that could counter the effects of abused drugs at these brain sites.

In 1993, NIDA-supported scientists cloned the mu opiate receptor, the primary brain site where opiates, including heroin, initiate euphoria. Subsequent research showed that buprenorphine, unlike heroin, only partially activates the mu receptor, while blocking other opiates from binding there. Clinical trials showed that buprenorphine reduced opiate use, had a low potential for abuse, and could be administered safely by physicians to patients in their offices. Additional pharmacological research engineered a combination tablet that blends buprenorphine with naloxone, a medication that completely blocks the mu receptor. The naloxone in this tablet can trigger withdrawal in opiate-dependent individuals but is activated only if the tablet is crushed and injected in an attempt achieve a more potent effect. This safety feature enables physicians to prescribe buprenorphine for long-term use in helping opiate-addicted patients reclaim stable, productive lives.

Why are Some People More Likely to Become Addicted to Drugs?

Personality traits--such as the desire to seek sensation--and genes play a role in vulnerability to drugs.

Even as NIDA's drug abuse prevention research continues to expand the range of programs that prevent initial drug use from early childhood to young adulthood, basic research and large-scale human studies are increasing knowledge of how genetic and environmental factors interact to increase or reduce the likelihood that someone will make the transition from drug use to abuse and addiction. This research pursues an ongoing question in drug abuse research: Why can some people stop using drugs after initial use, while others progress to drug abuse and addiction?

In the last decade, NIDA's vulnerability research program, which investigates the interaction of genetic and environmental factors that contribute to drug abuse and addiction, focused on this question. One major finding: Risk factors for experimenting with drugs and initial use differ from those that increase the risk of drug abuse and addiction. While social factors are more important in initial drug use, individual factors--genetics, personality, and certain mental disorders--are more important determinants of vulnerability to drug abuse and addiction.

Genetic research and brain imaging studies have identified genetically controlled variations in the neurobiology and chemistry of the brain reward system that affect whether individuals experience pleasant or unpleasant effects when first exposed to abused drugs. For some people, a heightened response to the rewarding effects of an abused drug on initial exposure may increase the likelihood of subsequent abuse and addiction. In addition, epidemiological research suggests certain childhood personality characteristics, such as shy-aggressive personalities, and preexisting mental disorders--including untreated attention-deficit/hyperactivity disorder, conduct disorder, depression, and anxiety--also increase the risk that an adolescent who begins to use drugs will transition from drug use to abuse and addiction.

This knowledge could dramatically increase the effectiveness of tomorrow's drug abuse and addiction prevention strategies. New research funded by NIDA and the National Institute of Mental Health will help determine if early treat-ment of mental disorders that make children more vulnerable to drug abuse can preclude that abuse.

Preventing Drug Abuse and Addiction

In 1992, the science of drug abuse prevention came of age. That year, NIDA-supported scientists published the first systematic classification of individual, family, neighborhood, and school factors that can increase or reduce a child's risk of drug abuse.

Identifying risk and protective factors for drug abuse gave NIDA researchers the information they needed to develop broad science-based family, school, and community drug abuse prevention programs. These programs have shown they can reduce rates of initial drug abuse among adolescents, the age group most vulnerable to drug experimentation. The benefits of these programs appear to be long-lasting, reducing the likelihood that children will develop more serious drug abuse problems. Researchers have enhanced the menu of broad drug abuse prevention programs with intensive approaches that help prevent drug abuse among adolescents who are at greater risk than their peers or to reduce use among those who have begun abusing drugs.

With a broad range of effective prevention approaches in hand for middle-schoolers, NIDA researchers are expanding the scope of prevention interventions to cover youths from early childhood through young adulthood. They are examining how the biological, behavioral, and social factors that influence the choice to abuse or avoid drugs change as children develop and mature.

Some interventions appear to mitigate personality traits or behaviors among younger children that are risk factors for later drug abuse, such as antisocial and aggressive behaviors. These interventions also appear to improve academic performance, a protective factor for later drug abuse. Future research will determine whether modifying risk and protective factors can prevent later abuse. At the other end of the developmental spectrum, another set of interventions is addressing social situations and factors most associated with alcohol and drug abuse among high school and college students.